Stencil sheet



' in Baltimore, in the county of Patented Mar. 16, 1926.-

PATENT OFFICE.

GUY LEONARD, OI BALTIMORE, MARYLAND. I

I STENCIL SHEET.

80 Drawing.

To all whom it may concern:

Be it known that I, GUY LEONARD, a subject of the King of Great Britain residing l3altimore and State of Maryland, have invented cer-. tain new and useful Improvements in Stencil Sheets, of which the following is a specification.

This invention relates to stencil-sheets for typewriting and stylographic'work.

The principal object of the invention isto produce at low cost an efficient, strong,

durable and economical stencil-sheet, which does not crack and will withstand crumpling and rough handling, and which is lastic and pliable and can be stenciled wit out dampening, but which will yield far more copies than an ordinary wax stencil-sheet. and which will cause the ink to be deposited sparingly on the stencil-co ies, thus improving the product and economizing ink and also avoiding the necessity of blotting the stencil-copies or of using anti-offset devices,

and which will preserve its good qualities both before and after empressing the stencil-characters thereon.

. The rawsheet or base of the stencil-sheet is loose-fibred paper, such as Yoshino, which is coated by using a liquid that includes a large proportion, say twenty parts by weight, of a 25 per cent shellac solution in methyl alcohol, although the strength of this solution may be varied. The shellac should be a good quality orange shellac. However, shellac solutions of diiferent qualities. and grades may be employed;

and the proportion of shellac solution used in the herein-disclosed formula maybe varied to suit. The strength of the shellac solution itself may also be varied. It will be understood that for dissolvingthe shellac, any suitable alcohol, acetone or amylacetate may be used. This solution is temporary, inasmuch as the alcohol eventually dries out of the coating'upon the stenoil-sheet. A

With the shellac solution is used a proportion of about eight parts by weight of a. glycerol fatty acid 7 ester, ,which may be triacetin, by the aid of which it is designed to secure great and permanent pliability and elasticity in the stencil-sheet. The triacetin is a lastifier, or renders the coating more plast1c, or gives it a' gummy qual ty. The shellac and chanical compound. Since alcohol-evapotriacetin form a mixture or me-' Application ma m 11, 1925. Serial a... cam.

late is also soluble in alcohol or .the other 7'0 common solvents, thus making with the shellac and triacetin a homogeneous, dry coating upon the evaporation of the alcohol or solvent.

While the specified proportions of the various ingredlents give excellent results, stillthe proportions may be varied within the scope of the invention. There is also rmissible some latitude of variation in the ingredients themselves, as, for example, glycerin may be used as a substitute softening agent, or a suitable oil, or, a suitable grease. Or the softenin agent dieth lphthalate may be modified y -glycerin, or y a suitable oil or grease. If deslred, a good substitute softening agent can be made of palm oil and stearic acid (or oleic acid) in the proportions of about 3 parts palm oil and about 2 parts stearic acid. When oil or stearic acid or oleic acid is. employed in softening,'sufiicient heat should be applied to secure a proper-solution.

The coating preparation. can be colored with any dye that is soluble in alcohol. or in a common solvent of the solution.

The coating solution may be prepared at ordinary room temperature, preferably by first mixing the liquid triacetin and diethylphthalate,-and then adding the shellac use lathe typewriting machine. 'Fortrans This bath may be be immersed; or-

portation, storage and handling, sheets of oil paper may be packed between the stencilsheets, whose tackiness, if present, is hardly appreciable. The oil sheet is preferably removed before inserting the stencil-sheet in the typewriter. Tackiness may be reduced J or eliminated by diminishing the proportion of shellac. The shellac, as well as being impervious to stenciling ink, binds or holds the other ingredients together. Other binding agents than shellac may be used, and ,con duce to toughness, durability and ink-resisting qualities of the stencil-sheet. trlacetin prevents the shellac from becoming brittle. The diethylphthalate softens or tempers the coating.

The typewriter-types make cleaner and narrower cuts in the stencil than usual heretofore, indicating the quality of elasticity imparted by the triacetin. The stencilsheet is highly economical of ink durin the operation of producing stencil-copies t ere-' from. There is no need to blot the stencilcopies or to interleave sheets therewith, or to use other anti-oifset devices. The stencilcopies can be handled at once, without danger of smearing the ink thereon. The

. stencil-sheet preserves its original form notwithstanding wrinkling, crumpling and rough handling; it is-elastic, and does not permanently stretch, nor do the fibres of the Yoshino tissue base loosen or pullapart. It is excellent for stylographic work as well as typcwriting.

In making copies from the typed or otherwise impressed stencil, very much less ink than heretofore reaches the stencil-copy, and hence the inked characters do not spread thereon and become unsightly, nor is blottin necessary, but the copies can be handled rig t away, or piled up, without smearing The pli'kofi'setting. There is a decided saving of The invention isfnot limited to the proportions given; andwithin the scope of the mvention various substitutes or equivalents ,may be used for the binding gum, the ester and the softener, as will be understood by those skilledin chemistry.

I claim:

1. A stencil-sheet of loose-fibered paper coated with a solution of shellac, triacetin and diethylphthalate.

2.- A stencil-sheet having a base of loose fibered paper provided with a dried homogeneous coating having by weight about five parts of shellac, eight parts of triacetin, and five parts of diethylphthalate.

3. A paper-coating bath including twenty parts by weight of twenty-five per cent shellac solution in methyl alcohol, eight parts by weight of triacetin, and five parts by weight of diethylphthalate.

4. A loose-fibered paper provided with a homogeneous coating of a glycerol fatty acid ester, diethylphthalate, and a binding agent.

'5. The process of dissolving shellac in alcohol, mixing in the solution glycerol fatty acid ester, and adding to the solution diethylp hthalate.

6.- he process of dissolving shellac in alcohol, mixing in the solution glycerol fatty acid ester, and addin to the solution diethylphthalate and a dye.

7. An ink-proof coating bath for paper, having twenty parts by' weight of a twenty-five per cent solution of orange shellac in methyl alcohol, about ei ht parts by weight of triacetin, and about five parts by weight of diethylphthalate.

GUY LEONARD. 

